Apparatus for spinning tubes



March 6, 1956 wHlTE 2,737,067

APPARATUS FOR SPINNING TUBES 2 Sheets-Sheet 1 Filed Dec. 50, 1949 INVENTOR. HAROLD A. WHITE.

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March 6, 1956 WHITE 2,737,067

' TUBES Filed Dec. 50, 1949 f XWJZ 4% ATTORNEYS United States Patent APPARATUS FOR SPINNING TUBES Harold A. White, St. Thomas, Ontario, Canada, assignor to The Weatherhead Company, Cleveland, Ohio, a corporation of Ohio Application December 30, 1949, Serial No. 135,903 7 Claims. (CI. 78-89) This invention relates to a spinning die, to the method of making and using such a die and more particularly to a spinning die designed to be rotated with respect to a metal tube so as to spin a closed rounded end on such tube.

It has heretofore been proposed to form a closed rounded end on a metal tube by moving a length of such tubular stock axially into a rotating die having a recess therein corresponding generally to the contour desired on the closed end of the tube, wherein the die is provided with openings or projections arranged to knead or work the metal of the tube. Such prior art spinning dies have presented certain disadvantages in connection with the difiiculty and cost involved in their manufacture and in the control of the heat of friction developed during the spinning of the tube. Other disadvantages relating to the rapid wear of the die and the control of the heat developed during spinning have adversely affected the general adoption of this type of apparatus for making closed rounded ends on tubular structures.

It-is among the objects of the present invention to provide a spinning die for tubes having an axial opening to receive the tube, wherein half of the opening is formed in each of two complementary die halves and onehalf of the opening is offset axially with respect to the other half.

It is a further object of the invention to provide a method of making a tube spinning die which comprises the forming of a symmetrical rounded opening at one end face of the cylindrical die block, cutting such die block in two halves along an axial plane so as to provide a die block made of two semi-cylindrical portions, and thereafter offsetting one semi-cylindrical portion with respect to the other, and thereafter grinding the projecting offset end faces of each semi-cylindrical portion so that onehalf of the opening in the die is larger than the other half so as to provide relief for the metal of the tube during spinning.

A further object of the invention is to provide a method of forming a closed rounded end on a metal tube by moving a length of tube axially into a rotating die cavity corresponding generally to the contour of the closed end of the tube, wherein the cavity is characterized by an eccentricity providing relief over one-half of the area of the cavity.

Further objects and advantages relating to economy in manufacture, efiiciency in operation and long die life will appear from the following description and the appended drawings, wherein:

Fig. 1 is a sectional view of the spinning die;

Fig. 2 is an end elevation;

Fig. 3 is a transverse sectional view taken on the plane 3-3 of Fig. 1;

Fig. 4 is an elevation of a metal tube with parts cut away illustrating the closed end formed on the tube in the die of Fig. 1;

Fig. 5 is a sectional view of a modified form of the invention which embodies a four part spinning die; and

Fig. 6 is a transverse sectional view taken on the plane 66 of Fig. 5. 7

Referring to the drawings, 5 indicates a die holder hav ing a shank 6 adapted to be rotated by a lathe, automatic screw machine or the like. The die holder is pro vided with a cylindrical bore 6a to receive the two complementary halves 7 and 8 of the die. The die parts 7 and 8 are proportioned to set against the bottom of the axial bore 6a and are retained therein by a lead collar 9 recessed at the end face of the die holder 5.

To secure the die halves 7 and 8 within the die holder, segmental locking blocks 10 and 11 are arranged within radial recesses 12 and 13, respectively, formed in the die holder 5. Allen screws or the like 14 and 15 extend radially into the recesses 12 and 13, respectively, and may be adjusted so that the elements 10 and 11 may be moved radially outward so that no part of the elements 10 or 11 project inwardly beyond the maximum diameter of the die halves 7 and 8. The blocks 10 and 11 are shown in Figures 1 and 3 at their innermost position where they fit within an annular groove in the die halves and serve to lock the two die halves 7 and 8 to each other and to restrain them from axial movement with respect to the die holder.

The lead collar 9 is locked in its recess on the end face of the die holder 5 by a key 16 fitting partly within the periphery of the lead collar 9 and partly within the die holder 5. The key is retained in place by a set-screw or the like 17.

The spinning die, which is here shown as comprising two halves 7 and 8, is provided with an axially extending reentrant opening or cavityindicated generally at 3.

One-half of the opening, namely 18a, is offset axially with respect to the other half of the opening indicated at 13b. The result of this arrangement is that the spinning die is relieved for at least half of the cavity area. An opening of this offset character may be formed in different ways. For instance, the die may be a solid cylindrical member rather than in the two halves 7 and 8, as illustrated, and a reentrant opening with offset half portions formed in such a solid cylindrical die.

The preferred method of making the die comprises forming a cylindrical die blank having an axial extent exceeding somewhat the axial extent of the die halves 7 and 8, and cutting a reentrant rounded die opening in such cylindrical die blank. Such an opening should be symmetrical with respect to the axis of the cylindrical die blank and should have a contour throughout corresponding to the contour desired on the closed end of the tube. Thereafter the die blank is cut on a plane through the longitudinal axis thereof and the two halves of the die blank oifset with respect to each other is indicated at 18c. This offset 18c is exaggerated somewhat for the purposes of illustration here and would vary through relatively narrow limits depending on the type of metal tube being worked in the die, the relative speed of rotation between the tube being worked and the spinning die, and the rate of axial movement of the tube into the die during the spinning thereof. For example, it has been determined that a brass tube having a diameter of .890 inch and a wall thickness of .085 inch may have a satisfactory rounded closed end formed thereon as shown in Fig. 4 in a die according to this invention where the offset between the two halves of the cavity, as at 18s, is about .008 inch. In the example referred to here, the die holder was rotating the die at about 1500 R. P. M. and the tubular stock was moved into and out of the die in two seconds.

Another method of forming the offset die cavity 13 comprises the forming of a symmetrical die cavity at the end face of a cylindrical blank. Thereafter the blank is cut along a plane through the axis of the blank so as to provide two identical halves. The cavity 18a in onehalf is thereafter enlarged or cut away so as to provide the axial offset as indicated in Fig. 1. The two halves are then assembled, as shown in Fig. l, and locked in the die holder.

The lead collar 9 is provided with a tapered opening 9a which merges through the land 91; into the die opening 18. The minimum diameter of the opening 9a is less than the outside diameter of the tube blank I) of Fig. 4 so that as the tube is moved axially into the lead collar the end portion thereof is frictionally heated and thus softened and rendered more plastic so as to facilitate the spinning thereof within the die opening 18.

in the modification shown in Figs. 5 and 6, the spinning die is made up of four complementary parts rather than the two complementary parts as described in connection with the first embodiment. This modification is like the first described form of the invention in that half of the die area is relieved. It is distinguished from the first described form of the invention in that the relief areas consist of 90 degree sectors or quadrants alternately arranged with respect to the metal working areas of the die. The holder 20 includes a shank 21 and is provided with a cylindrical bore 22 to receive the four complementary quadrants 23, 24, 25 and 26. The relief quadrants 2 and 26 are arranged, as shown in Fig. 6, so that a relief quadrant immediately follows a metal working quadrant as the die is being rotated to work the end of the tube. The four-part die of this modification is locked into position by locking segments 27 and 28 that engage the die quadrants 23-24 and 2526, respectively. The lead collar 29 is arranged at the entrance to the die and is proportioned with respect thereto to operate as described in connection with the first form of the invention. It will be understood that the quadrants of the four-part die are offset with respect to each other as indicated at 30 in Fig. 5 and that such a four-part die may he made up according to either of the methods heretofore described. it is among the advantages of this form of the invention that the degree of offset between the quadrants may be changed progressively around the die. This means that the relief quadrant 24 may be offset with respect to the metal working quadrant 25 an amount exceeding the offset between relief quadrant 26 and the metal working quadrant 25.

Although two forms of the invention have been shown and described in considerable detail, it will be appreciated that numerous modifications may be made therein without departing from the scope of the invention as defined in the following claims.

What is claimed:

1. A spinning die for closing metal tube ends comprising a die body, a cavity at one end face of the body, onehalf of said cavity having a fixed axial extent exceeding the axial extent of the other half so as toprovide a metal flow relief for the tube end being worked in the die.

2. A spinning die for metal tubes, a body, a fixed cavity circular in cross-section open at one end face of the body extending axially therein for a portion of the axial extent of the body, said cavity characterized by being made up of two similar half portions, one half portion being offset axially with respect to the other.

3. A spinning die for metal tubes comprising a body, a cavity circular in cross-section open at one end face of the body, one-half of said cavity having a fixed axial extent exceeding the axial extent of the other half so as to provide a metal flow relief for the tube end being worked in the die.

4. A spinning die for metal tubes, a body, a cavity at oneend face of the body extending axially therein for a portion of the axial extent of the blank, said cavity characterized by being made up of two similar parts having a fixed relationship relative to each other with the radius thereof decreasing progressively, the radius of one part decreasing at a rate exceeding the decrease in radius of the other part to provide a relief over one-half of the die cavity.

5. Apparatus for reducing the ends of metal tubes comprising a die holder, means to rotate the die holder about an axis longitudinal thereof, a recess in said holder open toward one end face thereof, a die proportioned to fit in said recess, said die having a cavity open toward said end face, said die consisting of two similar halves fixed relative to each other with a part of said cavity in each of said halves, the cavity part in one-half being offset axially with respect to the other cavity part, and means to secure the die halves to each other and to the holder.

6. Apparatus for reducing the ends of metal tubes comprising a die holder, means to rotate the die holder about an axis longitudinally thereof, a recess in said holder open toward one end face thereof, a die proportioned to fit in said recess, said die having a cavity open toward said end face, said die consisting of four similar quadrants fixed relative to each other with a part of said cavity in each of said quadrants, the cavity in one quadrant being oifset axially with respect to the cavity in the quadrant on each side thereof, and means to secure the quadrants to each other and to the holder.

7. A spinning die for metal tubes comprising a body, a fixed cavity circular in cross-section open at one end face of the body, one-fourth of said cavity having an axial extent exceeding the axial extent of the cavity portions at either side thereof so as to provide a metal flow relief for the tube end being worked in the die.

References Cited in the file of this patent UNITED STATES PATENTS 172,443 Ide Jan. 18, 1876 368,837 Kennedy Aug. 27, 1887 457,956 Kennedy Aug. 18, 1891 934,174 Hooker Sept. 14, 1909 1,280,823 Oster Oct. 8, 1918 1,790,829 McNaughton Feb. 3, 1931 2,239,425 Jacobson Apr. 22, 1941 2,256,912 Welch Sept. 23, 1941 2,309,561 Westin et al. Jan. 26, 1943 2,325,479 Crawford July 27, 1943 2,325,522 Lauer July 27, 1943 2,351,020 Dewey June 13, 1944 2,383,330 Michael Aug. 21, 1945 2,513,739 ONeill July 4, 1950 

